Numerous diseases and conditions in animals and humans are associated with insufficient differentiation of cells or with an insufficiency of cells. Many of these cells are derived from bone marrow. Such diseases and conditions include but are not limited to leukemia, lymphoma, and non-malignant blood disorders such as hemoglobinopathies, sickle cell disease, myelodysplastic syndrome and insufficient production of bone marrow derived cells following therapies such as radiation and chemotherapy.
Differentiation therapy of leukemia cells in diseases such as acute promyelocytic leukemia (APL), acute myeloid leukemia (AML), chronic promyelocytic leukemia (CPL) and chronic myeloid leukemia (CML), has provided an alternative strategy for the treatment of leukemia. In differentiation therapy, immature leukemia cells are induced by different chemical compounds to attain a mature phenotype resulting in arrest of their growth.
A number of differentiation compounds and also radiation have been reported to induce the differentiation of leukemia cells. Hemin, butyric acid, 5-azacytidine, cytosine arabinoside, hydroxyurea, guanosine, guanine, retinoic acid, trimidox, gamma-irradiation, mithramycin and chromomycin have been reported to induce differentiation of leukemia cells (Rutherford et al., Nature 280:164, 1979; Gambari et al., Biochem. Biophys. Acta, 886:203, 1986; Bianchi et al., Cancer Res. 46:6327, 1986; Adunyah et al., Biochem. Biophys. Acta, 1263:123, 1995; Osti et al., Haematologica 82:395, 1997; Cortesi et al., Eur. J. Haematol. 61:295, 1998; Iyamu et al., Biochem. Biophys. Res. Com. 247:759, 1998; Schwenke et al., Leuk. Res. 19:955, 1995; and Bianchi et al., Br. J. Haematol. 104:258, 1999).
Synthetic oligonucleotides are polyanionic sequences that are internalized in cells (Vlassov et al. Biochim. Biophys. Acta 1197:95, 1994). Synthetic oligonucleotides are reported to bind selectively to nucleic acids (Wagner, R. Nature: 372:333, 1994), to specific cellular proteins (Bates et al. J. Biol. Chem. 274:26369, 1999) and to specific nuclear proteins (Scaggiante et al. Eur. J. Biochem. 252:207, 1998), and to inhibit proliferation of cancer cells. Synthetic oligonucleotides have not been reported to possess differentiating activity on acute and/or chronic pro-myelocytic cells and/or myeloid leukemia cells. Synthetic phosphorothioate oligonucleotides having a CpG motif (5′purine-purine-cytosine (C)-guanine (G)-pyrimidine-pyrimidine3′) have been shown to induce the proliferation of B-cell chronic lymphocytic leukemia (Decker et al., Blood 95:999, 2000). Synthetic 27 base sequences containing G and variable amounts of thymine (T), hereinafter oligonucleotide GTn, wherein n is ≧1 or ≦7 Ts (Scaggiante et al., Eur. J. Biochem. 252:207, 1998), and wherein the number of bases is >20 (Morassutti et al., Nucleosides and Nucleotides 18:1711, 1999), have been reported to inhibit growth of leukemia cells by sequence specific binding to a 45 kDa nuclear protein. In contrast, GTn sequences, wherein the total number of bases is less than 15, are reported to be inactive against these cells (Morassutti et al. Nucleosides and Nucleotides 18:1711, 1999). Chimeric methylphosphonodiester/phosphodiester oligonucleotides of sequence type CGNNN (N=A, C, G or T)), introduced into the cytoplasm of cells by 10 minutes of reversible permeabilization with streptolysin O, induce apoptosis of human T cell leukemia cells. Nevertheless, the CGNNN oligonucleotides are reported to be inactive against three CML cell lines (K562, LAMA84 and KYO1), showing no significant effect on the growth and survival of these cells (Tidd et al., Nucleic Acid Res. 28:2242, 2000).
Depletion of bone marrow derived cells is observed in several conditions, including depletion following radiation therapy or chemotherapy. Insufficient production of cells destined to become erythrocytes or granulocytes is associated with numerous problems, including but not limited to, reduced delivery of oxygen to cells, decreased immune function, and clotting abnormalities. Various therapies, including expensive chemotherapies, are often required to stimulate production of red and white cells.
Most prior art differentiating therapies have proven to be less than adequate for clinical applications. Many of these therapies are inefficient or toxic, have significant adverse effects and are debilitating for the recipient. Therefore, there is a continuing need for novel compositions and methods that induce differentiation of cells such as myeloid-derived leukemia cells. What is also needed are new therapeutic compositions and methods that stimulate production and differentiation of pluripotent cells such as bone-marrow derived cells. Also needed are new therapeutic compositions that induce differentiation of cells. What is also needed are compositions and methods that may be used to treat diseases and conditions characterized by insufficient differentiation of cells or insufficient production of marrow derived cells.